Accuracy and Efficiency of a Dynamic Navigation System for Locating Calcified Canals

Accuracy and efficiency of dynamic navigated root-end resection in endodontic surgery: a pilot in vitro study

BACKGROUND

The operation accuracy and efficiency of dynamic navigated endodontic surgery were evaluated through in vitro experiments. This study provides a reference for future clinical application of dynamic navigation systems in endodontic surgery.

MATERIALS AND METHODS

3D-printed maxillary anterior teeth were used in the preparation of models for endodontic surgery. Endodontic surgery was performed with and without dynamic navigation by an operator who was proficient in dynamic navigation technology but had no experience in endodontic surgery. Optical scanning data were applied to evaluate the length and angle deviations of root-end resection. And the operation time was recorded. T tests were used to analyze the effect of dynamic navigation technology on the accuracy and duration of endodontic surgery.

RESULTS

With dynamic navigation, the root-end resection length deviation was 0.46 ± 0.06 mm, the angle deviation was 2.45 ± 0.96°, and the operation time was 187 ± 22.97 s. Without dynamic navigation, the root-end resection length deviation was 1.20 ± 0.92 mm, the angle deviation was 16.20 ± 9.59°, and the operation time was 247 ± 61.47 s. Less deviation was achieved and less operation time was spent with than without dynamic navigation (P < 0.01).

CONCLUSION

The application of a dynamic navigation system in endodontic surgery can improve the accuracy and efficiency significantly for operators without surgical experience and reduce the operation time.

Negotiation of Calcified Canals

The gradual formation of hard tissue along the root canal walls is a natural process associated with aging, typically progressing slowly over time. In reaction to tooth wear, operative procedures, vital pulp treatments, or regenerative endodontic procedures, hard tissue may also accumulate within the pulp canal space at a slow rate. In certain cases, such as dental trauma, autotransplantation, or orthodontic treatment, this deposition of hard tissue can accelerate unexpectedly, resulting in rapid narrowing or complete closure of the root canal space. This situation is called calcific metamorphosis (CM), root canal calcification, or pulp canal obliteration (PCO). Performing conventional endodontic therapy on severely calcified canals presents significant challenges and increases the risk of procedural accidents. Calcified canals introduce such complexity that dedicated negotiation concepts and specially designed instruments have been developed to deal with the challenge. This article seeks to review the existing methods for effectively navigating calcified canals and to introduce the buckling resistance activation test (BRAT) technique.

Artificial Intelligence in Endodontic Education

AIMS

The future dental and endodontic education must adapt to the current digitalized healthcare system in a hyper-connected world. The purpose of this scoping review was to investigate the ways an endodontic education curriculum could benefit from the implementation of artificial intelligence (AI) and overcome the limitations of this technology in the delivery of healthcare to patients.

METHODS

An electronic search was carried out up to December 2023 using MEDLINE, Web of Science, Cochrane Library, and a manual search of reference literature. Grey literature, ongoing clinical trials were also searched using ClinicalTrials.gov.

RESULTS

The search identified 251 records, of which 35 were deemed relevant to artificial intelligence (AI) and Endodontic education. Areas in which AI might aid students with their didactic and clinical endodontic education were identified as follows: 1) radiographic interpretation; 2) differential diagnosis; 3) treatment planning and decision-making; 4) case difficulty assessment; 5) preclinical training; 6) advanced clinical simulation and case-based training, 7) real-time clinical guidance; 8) autonomous systems and robotics; 9) progress evaluation and personalized education; 10) calibration and standardization.

CONCLUSIONS

AI in endodontic education will support clinical and didactic teaching through individualized feedback; enhanced, augmented, and virtually generated training aids; automated detection and diagnosis; treatment planning and decision support; and AI-based student progress evaluation, and personalized education. Its implementation will inarguably change the current concept of teaching Endodontics. Dental educators would benefit from introducing AI in clinical and didactic pedagogy; however, they must be aware of AI's limitations and challenges to overcome.

Mixed reality guided root canal therapy

Root canal therapy (RCT) is a widely performed procedure in dentistry, with over 25 million individuals undergoing it annually. This procedure is carried out to address inflammation or infection within the root canal system of affected teeth. However, accurately aligning CT scan information with the patient's tooth has posed challenges, leading to errors in tool positioning and potential negative outcomes. To overcome these challenges, a mixed reality application is developed using an optical see-through head-mounted display (OST-HMD). The application incorporates visual cues, an augmented mirror, and dynamically updated multi-view CT slices to address depth perception issues and achieve accurate tooth localization, comprehensive canal exploration, and prevention of perforation during RCT. Through the preliminary experimental assessment, significant improvements in the accuracy of the procedure are observed. Specifically, with the system the accuracy in position was improved from 1.4 to 0.4 mm (more than a 70% gain) using an Optical Tracker (NDI) and from 2.8 to 2.4 mm using an HMD, thereby achieving submillimeter accuracy with NDI. 6 participants were enrolled in the user study. The result of the study suggests that the average displacement on the crown plane of 1.27 ± 0.83 cm, an average depth error of 0.90 ± 0.72 cm and an average angular deviation of 1.83 ± 0.83°. Our error analysis further highlights the impact of HMD spatial localization and head motion on the registration and calibration process. Through seamless integration of CT image information with the patient's tooth, our mixed reality application assists dentists in achieving precise tool placement. This advancement in technology has the potential to elevate the quality of root canal procedures, ensuring better accuracy and enhancing overall treatment outcomes.

Comparing accuracy in guided endodontics: dynamic real-time navigation, static guides, and manual approaches for access cavity preparation - an in vitro study using 3D printed teeth

OBJECTIVES

To assess root canal localization accuracy using a dynamic approach, surgical guides and freehand technique in vitro.

MATERIALS AND METHODS

Access cavities were prepared for 4 different 3D printed tooth types by 4 operators (n = 144). Deviations from the planning in angle and bur positioning were compared and operating time as well as tooth substance loss were evaluated (Kruskal-Wallis Test, ANOVA). Operating method, tooth type, and operator effects were analyzed (partial eta-squared statistic).

RESULTS

Angle deviation varied significantly between the operating methods (p < .0001): freehand (9.53 ± 6.36°), dynamic (2.82 ± 1.8°) and static navigation (1.12 ± 0.85°). The highest effect size was calculated for operating method (ηP²=0.524), followed by tooth type (0.364), and operator (0.08). Regarding deviation of bur base and tip localization no significant difference was found between the methods. Operating method mainly influenced both parameters (ηP²=0.471, 0.379) with minor effects of tooth type (0.157) and operator. Freehand technique caused most substance loss (p < .001), dynamic navigation least (p < .0001). Operating time was the shortest for freehand followed by static and dynamic navigation.

CONCLUSIONS

Guided endodontic access may aid in precise root canal localization and save tooth structure.

CLINICAL RELEVANCE

Although guided endodontic access preparation may require more time compared to the freehand technique, the guided navigation is more accurate and saves tooth structure.

Limitations and Management of Dynamic Navigation System for Locating Calcified Canals Failure

Nonsurgical endodontic teeth treatment with severe pulp canal obliteration poses challenges, primarily locating canals. By combining 3-dimensional reconstruction and spatial location registration, the dynamic navigation technique uses an optical tracking system to guide the clinician to drill in real time according to the predesigned path until access to the canal is established. Several in vitro studies and case reports have shown that calcified canal location with dynamic navigation system (DNS) is more accurate and efficient, yet the technique has limitations. In 4 cases with 7 teeth, this work presents manipulation process and clinical outcomes of DNS helping in calcified canal location. We performed handpiece adaptation and elucidated the failure to locate the canals with DNS in 2 teeth, resulting in canal geometry alteration and canal path deviation. Subsequently, the more experienced endodontist located the canals by combining cone-beam computed tomographic imaging and dental operating microscopy. All patients were completely asymptomatic after treatment. At the 1-year follow-up visit, the bone healing of periapical lesions progressed well according to the periapical radiography or cone-beam computed tomographic imaging. These findings indicate that DNS is a promising technique for locating calcified canals; however, it needs to be refined before clinical use.

Expert consensus on digital guided therapy for endodontic diseases

Digital guided therapy (DGT) has been advocated as a contemporary computer-aided technique for treating endodontic diseases in recent decades. The concept of DGT for endodontic diseases is categorized into static guided endodontics (SGE), necessitating a meticulously designed template, and dynamic guided endodontics (DGE), which utilizes an optical triangulation tracking system. Based on cone-beam computed tomography (CBCT) images superimposed with or without oral scan (OS) data, a virtual template is crafted through software and subsequently translated into a 3-dimensional (3D) printing for SGE, while the system guides the drilling path with a real-time navigation in DGE. DGT was reported to resolve a series of challenging endodontic cases, including teeth with pulp obliteration, teeth with anatomical abnormalities, teeth requiring retreatment, posterior teeth needing endodontic microsurgery, and tooth autotransplantation. Case reports and basic researches all demonstrate that DGT stand as a precise, time-saving, and minimally invasive approach in contrast to conventional freehand method. This expert consensus mainly introduces the case selection, general workflow, evaluation, and impact factor of DGT, which could provide an alternative working strategy in endodontic treatment.

Accuracy of computer-assisted dynamic navigation when performing coronectomy of the mandibular third molar: A pilot study

OBJECTIVES

The study represents a preliminary evaluation of the accuracy of the dynamic navigation system (DNS) in coronectomy of the mandibular third molar (M3M).

METHODS

The study included participants with an impacted M3M near the inferior alveolar canal. The coronectomy planes were designed before the surgery using cone-beam computed tomography (CBCT) imaging data and then loaded into the DNS program. Intraoperatively, the navigation system was used to guide the complete removal of the target crown. Postoperative CBCT imaging was used to assess any three-dimensional deviations of the actual postoperative from the planned preoperative section planes for each patient.

RESULTS

A total of 12 patients (13 teeth) were included. The root mean square (RMS) deviation of the preoperatively designed plane from the actual postoperative surface was 0.69 ± 0.21 mm, with a maximum of 1.45 ± 0.83/-1.87 ± 0.63 mm deviation. The areas with distance deviations < 1 mm, 1-2 mm, and 2-3 mm were 71.97 ± 5.72 %, 22.96 ± 6.57 %, and 4.52 ± 2.28 %, respectively. Most patients showed extremely high convexity of the surface area located in the mesial region adjacent to the base of the extraction socket. There was no observable evidence of scratching of the buccolingual bone plate at the base of the extraction socket by the handpiece drill.

CONCLUSIONS

These results provide preliminary support for the use of DNS-based techniques when extracting M3M using a buccal approach. This would improve the accuracy of coronectomy and reduce the potiential damage to the surrounding tissue.

CLINICAL SIGNIFICANCE

DNS is effective for guiding coronectomy.

A literature review of local and systemic considerations for endodontic treatments in older adults

OBJECTIVES

The aim of this literature review was to summarise the clinical important findings on the endodontic treatment outcome in older patients (≥60 years old) with pulpal/periapical disease considering local and systemic factors from a body of knowledge that is heterogeneous in methods or disciplines.

BACKGROUND

Due to the increasing number of older patients in the endodontic practice, and the current trend for tooth preservation, the need for clinicians to have a better understanding of age-related implications that may influence the required endodontic treatment in older adults to retain their natural dentition is indispensable.

METHODS

PubMed/Medline and Embase was searched by a medical librarian using specific terms based on inclusion/exclusion criteria. The reference list was hand-seached for additional relevant publications between 2005-2020. A combination of these terms was performed uing Boolean operators and MeSH terms.

RESULTS

Of the 1577 publications identified manually and electronically, 25 were included to be fully reviewed by the examiners. The data was derived from three systematic reviews, one systematic and meta-analysis, three case series, four prospective and 14 retrospective cohorts. Overall, there was heterogeneity in reporting as well as limitations in most studies.

CONCLUSIONS

The outcome of endodontic treatment (ET) either nonsurgical or surgical or combination of these is not affected by older age. ET can be the treatment of choice in older patients wiht pulpal/periapical disease. There is no evidence that older age per se affects the outcome of any type of endodontic treatment.

Dynamic Navigation System vs. Free-Hand Approach in Microsurgical and Non-Surgical Endodontics: A Systematic Review and Meta-Analysis of Experimental Studies

(1) Background: A Dynamic Navigation System (DNS) is an innovative tool that facilitates the management of complex endodontic cases. Despite the number of advantages and limitations of this approach, there is no evidence-based information about its efficiency in comparison with that of the traditional method in endodontics. (2) Objectives: We aimed to explore any beneficial effects of the DNS and compare the outcomes of DNS vs. free-hand (FH) approaches for non-surgical and microsurgical endodontics. (3) Methods: A literature search was conducted in August 2023 to identify randomized, experimental, non-surgical, and microsurgical endodontic studies that compared the DNS with FH approaches. The procedural time (ΔT, s), substance loss (ΔV, mm3), angular deviation (ΔAD, °), coronal/platform linear deviation (ΔLD_C, mm), and apical linear deviation (ΔLD_A, mm) were recorded and analyzed. Quality and risk of bias assessments were conducted according to the Quality Assessment Tool For In Vitro Studies. A meta-analysis was performed using mean difference and standard deviation for each outcome, and heterogeneity (I2) was estimated. p < 0.05 was considered significant. (4) Results: One-hundred and forty-six studies were identified following duplicate removal, and nine were included in the systematic review and meta-analysis. The overall risk of bias was classified as low. The DNS was found to be more accurate and efficient than the FH approach was, resulting in a significantly shorter operation time (p < 0.00001) and less angular (p ≤ 0.0001) and linear deviation (p ≤ 0.01). For substance loss, the advantage of the DNS was significant only for microsurgery (p = 0.65, and p < 0.005, for non-surgical and microsurgical procedures, respectively). A reduced risk of iatrogenic failure using the DNS was observed for both expert and novice operators. (5) Conclusions: The DNS appears beneficial for non-surgical and microsurgical endodontics, regardless of the operator's experience. However, appropriate training and experience are necessary to access the full advantages offered by the DNS.

Accuracy and Efficiency of Endodontic Microsurgery Assisted by Dynamic Navigation Based on Two Different Registration Methods: An In Vitro Study

INTRODUCTION

This study aimed to compare the accuracy and efficiency of dynamic navigation-assisted endodontic microsurgery (DN-EMS) using two different registration methods.

METHODS

Three-dimensional-printed jaw models, including 40 teeth, were divided into two groups (n = 20). Cone-beam computed tomography images of all teeth were scanned under the same exposing parameters. An endodontic dynamic navigation system (DHC-ENDO1) was used to plan the drilling paths. Dynamic navigation-assisted endodontic microsurgery (DN-EMS) was performed using either U-shaped tube (UT) or tooth cusp (TC) registration method. The accuracy was determined by platform deviation, end deviation, angular deviation, resection angle, and resection length deviation. The registration efficiency was defined as the time required to complete the registration procedure. Osteotomy volume of each resection was calculated by Mimics 21.0. Statistical analyses were performed using IBM SPSS Statistics 24.0. Comparisons between groups were performed using the independent sample t test or Mann-Whitney U test. P < .05 was adopted as significant difference.

RESULTS

The UT group was significantly more accurate in terms of mean platform deviation, end deviation, angular deviation, and resection angle (P < .05). Resection length deviation did not differ significantly between the registration groups. The UT group was significantly more efficient than the TC group (P < .05). No significant differences were found in the osteotomy volumes between the two groups.

CONCLUSIONS

In the model-based surgical simulation comparison, DN-EMS based on UT registration is more accurate and efficient than the TC method but requires an additional registration device. TC technique may be a reasonable alternative to UT registration in certain clinical tasks.

Assessment of guide fitting using an intra-oral scanner: An in vitro study

OBJECTIVES

The aim of this study was to evaluate the capacity of an intra-oral scanner (IOS) to assess the position of an endodontic guide in vitro.

METHODS

Fourteen extracted human teeth were placed into a maxillary model and scanned using computed tomography and a reference laboratory scanner. An ideal endodontic guide was then created and modified by adding defects of different thicknesses to simulate incorrect positions: 50 μm, 150 μm, 400 μm, and 1000 μm. For each thickness, guides were printed three times and each guide was scanned by three experimented operators using a Trios 4 IOS (3Shape, Copenhagen, Denmark). The 36 scans were compared using a best-fit alignment to the master model without defect to define the accuracy of the method and the positioning error.

RESULTS

The IOS presented a mean trueness of 1.28 μm (SD= 12.70) and a mean precision of 11.52 μm (SD= 62.17). Considering all sizes of defect, the mean measured position of the endodontic guide was highly correlated (R>0.99) with the expected position. Compared to the ideal guide, there was a mean linear deviation of 46.11 μm (SD= 23.21) and a mean angular deviation of 5.9° (SD= 1.2); this deviation was not influenced by the operator.

CONCLUSION

The present study found that an IOS had good performance to detect a positioning error of the endodontic guide in vitro.

CLINICAL SIGNIFICANCE

This new application of IOS has a promising potential in clinical practice to assist practitioners during the fitting of guides.

Current Applications of Dynamic Navigation System in Endodontics: A Scoping Review

This scoping review (SCR) was conducted to map the existing literature on dynamic navigation system (DNS), to examine the extent, range, and nature of research activity. Additionally, this SCR disseminates research findings, determines the value of conducting a full systematic review with meta-analysis, and identifies gaps in the existing literature and future directions. This SCR followed Arksey and O'Malley's five stages framework. The electronic search was performed in PubMed (Medline), Scopus (Elsevier), and Web of Science (Clarivate Analytics) databases using a search strategy. Five themes emerged during the descriptive analysis that captured the DNS application in endodontics. The DNS has been explored for creating access cavities (8/18, 44.44%), locating calcified canals (4/18, 22.2%), microsurgery (3/18, 16.6%), post removal (2/18, 11.1%), and intraosseous anesthesia (1/18, 5.5%). Out of the 18 studies included, 12 are in vitro (66.6%), five are in vivo (case report) (27.7%), and one is ex vivo (5.5%). The DNS demonstrated accuracy and efficiency in performing minimally invasive access cavities, locating calcified canals, and performing endodontic microsurgery, and it helped target the site for intraosseous anesthesia.

Effect of field of view and voxel size on CBCT-based accuracy of dynamic navigation in endodontic microsurgery: an in vitro study

INTRODUCTION

This study aimed to evaluate the influence of field of view (FOV) and voxel size on the accuracy of dynamic navigation (DN)-assisted endodontic microsurgery (EMS).

METHODS

Nine sets of maxillary and mandibular three-dimensional-printed jaw models composed of 180 teeth were divided into nine groups with different FOVs (80 × 80 mm, 60 × 60 mm, and 40 × 40 mm) and voxel sizes (0.3, 0.16, and 0.08 mm). The endodontic DN system was used to plan and execute the EMS. The accuracy of the DN-EMS was represented by the platform deviation, end deviation, angular deviation, resection angle, and resection length deviation. Statistical analyses were performed using SPSS 24.0, and the significance level was set at p < 0.05.

RESULTS

The average platform, end, angular, resection angle, and resection length deviation were 0.69 ± 0.31 mm, 0.93 ± 0.44 mm, 3.47 ± 1.80°, 2.35 ± 1.76°, and 0.41 ± 0.29 mm, respectively. No statistically significant differences in accuracy were observed between the nine FOV and voxel size groups.

CONCLUSION

FOV and voxel size did not appear to play an important role in the accuracy of DN-EMS. Considering the image quality and radiation dose, it is reasonable to select a limited FOV (such as 40 × 40 mm and 60 × 60 mm) to cover only the registration device, involved teeth, and periapical lesion. The voxel size should be selected according to the required resolution and CBCT units.

Guided Endodontic Surgery: A Narrative Review

Background and objectives: Endodontic surgery has evolved over the last two decades. The use of state-of-the-art guided endodontic surgical procedures produces a predictable outcome in the healing of lesions of endodontic origin. The main objective of this review paper is to define and characterize guided surgical endodontics as well as its benefits and drawbacks by reviewing the most recent relevant scientific literature. Methods: A literature search was conducted using multiple databases comprising of MEDLINE (via PubMed), EMBASE, and Web of Science. The terms used for the search were ‘guided endodontics’, ‘surgical endodontics’, and ‘endodontic microsurgery’. Results: In total, 1152 articles were obtained from the analysis of the databases. Unrelated articles from the available full text of 388 articles were excluded. A total of 45 studies were finally included in the review. Conclusions: Surgical-guided endodontics is a relatively new area of study that is still maturing. It has many applications such as root canal access and localization, microsurgical endodontics, endodontic retreatment, and glass fiber post removal. Additionally, it does not matter how experienced the operator is; the procedure can be completed for the patient in less time and provides greater accuracy and safety than conventional endodontics.

Real-time guided endodontics: A case report of maxillary central incisor with calcific metamorphosis

Dental trauma results in various complications and poses an enigma to the practitioner. Calcific metamorphosis is one of the sequelae of trauma. A female patient of 35 years visited the specialty clinic of endodontics for the management of a discolored tooth. Clinically, discolored 21 was observed with no pain on palpation and percussion. The pulp sensibility test revealed a negative response. Radiographic examination revealed pulp canal obliteration with an apical radiolucency of Peri Apical Index (PAI 4). The tooth was diagnosed as necrotic pulp with asymptomatic apical periodontitis. Attempt to negotiate the canal under a Dental Operating Microscope (LABOMED, Los Angeles, CA, USA) and ultrasonics (Satelec, Acteon, France) was futile. Cone-beam computed tomography image revealed a patent canal in the apical third. Using real-time guided endodontics with a dynamic navigation system (Navident, ClaroNav, Toronto, ON, Canada), the protocol of plan, trace, and place was followed, and successful canal negotiation was achieved. After radiographic confirmation, root canal treatment was completed.

Evaluation of a dynamic navigation system for endodontic microsurgery: study protocol for a randomised controlled trial

INTRODUCTION

Endodontic microsurgery is a very important technique for preserving the natural teeth. The outcomes of endodontic microsurgery largely depend on the skill and experience of the operators, especially for cases in which the apices are located far away from the labial/buccal cortical bone. A dynamic navigation system (DNS) could provide a more accurate and efficient way to carry out endodontic microsurgery. This study is devoted to comparing the clinical outcomes of the DNS technique with those of the freehand technique.

METHODS AND ANALYSIS

Sixteen patients will be randomly assigned to one of two groups. For the experimental group, the osteotomy and root-end resection will be performed under the guidance of dynamic navigation. For the control group, these procedures will be performed freehand by an endodontist. The required time to perform these procedures will be used to evaluate the efficiency of the DNS technique. A Visual Analogue Scale will be used to evaluate pain at 1, 3 and 7 days after endodontic microsurgery. Preoperative and postoperative cone beam CT scans will be obtained to evaluate the accuracy of the DNS technique. The global coronal deviations, the apical deviations and the angular deflection will be measured. The root-end resection length deviation, the root-end resection angle deviations, the extent of the osteotomy and the volume change of the buccal cortical bone will also be measured. Periapical radiographs will be obtained to evaluate the outcome at 1 year after microsurgery. The time to execute the study, including follow-ups, will last from 1 June 2022 to 31 December 2025.

ETHICS AND DISSEMINATION

The present study has received approval from the Ethics Committee of Peking University School and Hospital of Stomatology. The results will be disseminated through scientific journals.

TRIAL REGISTRATION NUMBER

ChiCTR2200059389.

Guided Endodontics: A Literature Review

The main objective of this paper is to perform an updated literature review of guided endodontics based on the available up-to-date scientific literature to identify and describe the technique, its benefits, and its limitations. Four electronic databases (PubMed, Scopus, Science Direct, and Web of Science) were used to perform a literature search from 1 January 2017 to 13 May 2022. After discarding duplicates, out of 1047 results, a total of 29 articles were eligible for review. Guided endodontics is a novel technique that is currently evolving. It is applied in multiple treatments, especially in accessing and locating root canals in teeth with pulp canal obliteration, microsurgical endodontics, and removing glass fiber posts in endodontic retreatments. In addition, it is independent of an operator's experience, requires less treatment time for the patient, and is more accurate and safer than conventional endodontics.

Present status and future directions - Guided endodontics

Luxation injuries and other stimuli may lead to a pulp canal obliteration (PCO). Even though the apposition of tertiary dentine is a sign of a vital pulp, in some cases root canal treatment is indicated in the long term due to apical periodontitis or pulpitis. Depending on the extent of PCO, root canal treatment may be challenging even for experienced and well-equipped endodontic specialists. The 'guided endodontics' (GE) technique was introduced 6 years ago as an alternative to conventional access cavity preparation for teeth with PCO and apical pathosis or irreversible pulpitis. Using three-dimensional radiological imaging such as cone-beam computed tomography and a digital surface scan, an optimal access to the orifice of the calcified root canal can be planned virtually with appropriate software. GE is implemented either with the help of templates analogous to guided implantology (= static navigation) or by means of dynamic navigation based on a camera-marker system. GE has emerged as a field of research in the last 6 years with very promising laboratory-based results regarding the accuracy of guided endodontic access cavities for both static and dynamic navigation. Clinical implementation seems to provide favourable results, but the evidence is mainly based on numerous case reports and a few case series. This narrative review aims to provide an update on the present status of GE and to identify relevant research areas that could contribute to further improvements of this technique.

Guided Endodontics: Static vs. Dynamic Computer-Aided Techniques—A Literature Review

(1) Background: access cavity preparation is the first stage of non-surgical endodontic treatment. The inaccuracy of this step may lead to numerous intraoperative complications, which impair the root canal treatment’s prognosis and therefore the tooth’s survival. Guided endodontics, meaning computer-aided static (SN) and dynamic navigation (DN) techniques, has recently emerged as a new approach for root canal location in complex cases. This review aims to compare SN and DN guided endodontics’ techniques in non-surgical endodontic treatment. (2) Methods: an electronic search was performed on PubMed, Scopus, and Cochrane Library databases until October 2021. Studies were restricted by language (English, Spanish and Portuguese) and year of publication (from 2011 to 2021). (3) Results: a total of 449, 168 and 32 articles were identified in PubMed, Scopus, and Cochrane Library databases, respectively, after the initial search. Of the 649 articles, 134 duplicates were discarded. In this case, 67 articles were selected after title and abstract screening, of which 60 were assessed for eligibility through full-text analysis, with one article being excluded. Four cross-references were added. Thus, 63 studies were included. (4) Conclusions: guided endodontics procedures present minimally invasive and accurate techniques which allow for highly predictable root canal location, greater tooth structure preservation and lower risk of iatrogenic damage, mainly when performed by less experienced operators. Both SN and DN approaches exhibit different advantages and disadvantages that make them useful in distinct clinical scenarios.

Treatment of Pulp Canal Obliteration Using a Dynamic Navigation System: Two Case Reports

Endodontic treatment of calcified canals presents a major challenge because of the high incidence of complications, such as perforation, canal geometry alteration, and loss of dental hard tissue. The dynamic navigation technique uses an optical tracking system for real-time navigation to guide the operator to drill according to the preoperative plan and obtain access to the calcified canals. This article describes in detail the use, advantages, disadvantages, and limitations of a novel dynamic navigation system (DNS) in two cases with severely calcified canals. The findings in these cases demonstrate that DNS is a promising technique for the location of calcified root canals.

Accuracy of Dynamic Navigation for Non-Surgical Endodontic Treatment: A Systematic Review

In recent years, the application of Guided Endodontics has gained interest for non-surgical endodontic treatment and retreatment. The newest research focuses on the accuracy of Dynamic Navigation (DN). This article systematically reviewed existing data on the accuracy of non-surgical endodontic treatment procedures that were completed using DN. Following the PRISMA criteria, an electronic database search was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Studies comparing the accuracy of non-surgical endodontic treatment using DN and the conventional freehand technique were eligible. The literature search resulted in 176 preliminary records. After the selection process six studies were included. The risk of bias was evaluated using the modified Cochrane Collaboration Risk of Bias 2.0 tool. Five studies examined the aid of DN for planning and executing endodontic access cavities, and one for fiber post removal. In two studies, endodontic access cavities were performed in teeth with pulp canal obliteration. The main outcomes that were measured in the included studies were preparation time, global coronal entry point and apical endpoint deviations, angular deviation, tooth substance loss, qualitative precision, number of unsuccessful attempts or procedural mishaps. The risk of bias was rated from low to raising some concerns. Overall, DN showed increased accuracy compared to the freehanded technique and could be especially helpful in treating highly difficult endodontic cases. Clinical studies are needed to confirm the published in vitro data.

REAL-TIME 3D IMAGE-GUIDED NAVIGATION SYSTEM IN ENDODONTIC MICROSURGERY - A CADAVER STUDY

INTRODUCTION

This study evaluated the accuracy and efficiency of 3D Dynamic Navigation System (3D-DNS) to perform minimally invasive osteotomy (MIO) and root-end resection (RER) in endodontic microsurgery (EMS) and investigated the viability of root-end cavity preparation (RECP) and fill (REF) in MIO.

METHODS

We divided 48 tooth roots in cadaver heads into two groups: 3D-DNS (n = 24) and freehand (n = 24). Cone beam computed tomography (CBCT) scans were taken before and after surgery. First, we verified virtual 3D-DNS accuracy using three outcome measures: 2D and 3D virtual deviations and angular deflection (AD). Second, we investigated 3D-DNS's accuracy for performing MIO in two outcome measures: Osteotomy size and volume. Third, we determined the 3D-DNS accuracy for RER in three outcomes: Resected root length, root length after resection, and resection angle. We investigated the viability of RECP and REF and measured REF depth and volume, as well, recording procedural times and number of mishaps.

RESULTS

2D and 3D virtual deviations and AD were lower in the 3D-DNS than FH (p<.05). Osteotomy height, length, and volume were all reduced when using 3D-DNS (p < .05). The resection angle was lower for the 3D-DNS (p<.05). RECP and REF were completed in 100% of the roots. The REF depth achieved was ∼ 3mm. Osteotomy time, RER time, and total procedure time were all significantly shortened using 3D-DNS (p < .05).

CONCLUSIONS

3D-DNS enabled our surgeon to perform accurate and efficient EMS with minimally invasive osteotomy and RER. The surgeon was also able to conduct RECP with adequate REF in minimally invasive osteotomy performed using 3D-DNS guidance.

Present status and future directions - Minimal endodontic access cavities

In the last decades, the move of Medicine towards minimally invasive treatments is notorious and scientifically grounded. As Dentistry naturally follows its footsteps, minimal access preparation also became a trend topic in the endodontic field. This procedure aims to maximize preservation of dentine tissue, backed up by the idea that this is an effective way to reduce the incidence of post-treatment tooth fracture. However, with the assessment of the body of evidence on this topic, it is possible to observe some key-points (a) the demand for nomenclature standardization, (b) the requirement of specific tools such as ultra-flexible instruments, visual magnification, superior illumination, and three-dimensional imaging technology, (c) minimally invasive treatment does not seem to affect orifice location and mechanical preparation when using adequate armamentarium, but it (d) may impair adequate canal cleaning, disinfection, and filling procedures, and also (e) it displays contradictory results regarding the ability to increase the tooth strengthen compared to the traditional access cavity. In spite of that, it is undeniable that methodological flaws of some benchtop studies using extracted teeth may be responsible for the conflicting data, thus triggering the need for more sophisticated devices/facilities and specifically designed research in an attempt to make it clear the role of the access size/design on long-term teeth survival. Moreover, it is inevitable that a clinical approach like minimal endodontic access cavities that demands complex tools and skilled and experienced operators bring to the fore doubts on its educational impact mainly when confronted with the conflicting scientific output, ultimately provoking a cost-benefit analysis of its implementation as a routine technique. In addition, this review discusses the ongoing scientific and clinical status of minimally invasive access cavities aiming to input an in-depth and unbiased view over the rationale behind them, uncovering not only the related conceptual and scientific flaws, but also outlining future directions for research and clinical practices. The conclusions attempt to skip from passionate disputes highlighting the current body of evidence as weak and incomplete to guide decision making, demanding the development of a close-to-in-situ laboratory model or a large and well-controlled clinical trial to solve this matter.

Guided endodontics: accuracy of access cavity preparation and discrimination of angular and linear deviation on canal accessing ability-an ex vivo study

BACKGROUND

Guided endodontics technique has been introduced for years, but the accuracy in different types of teeth has yet to be assessed. The aim of this study is to evaluate the accuracy of three dimensional (3D)-printed endodontic guides for access cavity preparation in different types of teeth, and to evaluate the predictive ability of angular and linear deviation on canal accessibility ex vivo.

METHOD

Eighty-four extracted human teeth were mounted into six jaw models and categorised into three groups: anterior teeth (AT), premolar (P), and molar (M). Preoperative cone beam computed tomography (CBCT) and surface scans were taken and matched using implant planning software. Virtual access cavity planning was performed, and templates were produced using a 3D printer. After access cavities were performed, the canal accessibility was recorded. Postoperative CBCT scans were superimposed in software. Coronal and apical linear deviations and angular deviations were measured and evaluated with nonparametric statistics. The receiver operating characteristic (ROC) curve was used to evaluate the predictive ability of angular and linear deviation for canal accessibility in SPSS v20.

RESULTS

A total of 117 guided access cavities were created and 23 of them were record as canal inaccessibility, but all canals were accessible after canal negotiation. The average linear deviation for all groups was 0.13 ± 0.21 mm at coronal position, 0.46 ± 0.4 mm at apical position, and 2.8 ± 2.6° in angular deviation. At the coronal position, the linear deviations of the AT and P groups were significantly lower than M group deviation (P < 0.05), but no statistically significant difference between AT group and P group. The same results were found in linear deviation at the apical position and in angular deviation. The area under the ROC curve was 0.975 in angular deviation, 0.562 in linear deviation at the coronal position, and 0.786 at the apical position. Statistical significance was noted in linear deviation at the apical position and in angular deviation (P < 0.001).

CONCLUSIONS

In conclusion, this study demonstrated that the accuracy of access cavity preparation with 3D-printed endodontic guides was acceptable. The linear and angular deviations in the M group were significantly higher than those in the other groups, which might be caused by the interference of the opposite teeth. Angular deviation best discriminated the canal access ability of guided access cavity preparation.

Integration of imaging modalities in digital dental workflows - possibilities, limitations, and potential future developments

The digital workflow process follows different steps for all dental specialties. However, the main ingredient for the diagnosis, treatment planning and follow-up workflow recipes is the imaging chain. The steps in the imaging chain usually include all or at least some of the following modalities: cone-beam computed tomographic data acquisition, segmentation of the cone-beam computed tomography image, intraoral scanning, facial three-dimensional soft tissue capture and superimposition of all the images for the creation of a virtual augmented model. As a relevant clinical problem, the accumulation of error at each step of the chain might negatively influence the final outcome. For an efficient digital workflow, it is important to be aware of the existing challenges within the imaging chain. Furthermore, artificial intelligence-based strategies need to be integrated in the future to make the workflow more simplified, accurate and efficient.

Real-Time Guided Endodontics with a Miniaturized Dynamic Navigation System Versus Conventional Freehand Endodontic Access Cavity Preparation: Substance Loss and Procedure Time

INTRODUCTION

This study aimed to evaluate substance loss and the time required for access cavity preparation (ACP) using the conventional freehand method (CONV) versus a miniaturized dynamic navigation system of real-time guided endodontics (RTGE) in an in vitro model using 3-dimensional-printed teeth.

METHODS

Nine human anterior maxillary teeth were selected and micro-computed tomographic scanned. Root canals were virtually reduced to 2 mm below the cementoenamel junction. The teeth were digitally duplicated and mirrored to yield 6 different models with 6 single-rooted teeth each. The models were 3-dimensionally printed using radiopaque resin and consecutively mounted on a dental mannequin for ACP. Two operators with 12 and 2 years of clinical experience, respectively, received 6 models (36 teeth) each and performed ACP on half of the models using RTGE (after digital planning) and CONV on the other half 2 weeks later. The time was recorded. Postoperative substance loss was measured by cone-beam computed tomographic imaging. The differences in time and substance loss between the methods and operators were evaluated by the t test.

RESULTS

Overall, substance loss was significantly lower with RTGE than CONV (mean = 10.5 mm³ vs 29.7 mm³), but both procedures took a similar time per tooth (mean = 195 vs 193 seconds). Operator 1 (more experienced) achieved significantly less substance loss than operator 2 with CONV (mean = 19.9 vs 39.4 mm³) but not with RTGE (mean = 10.3 vs 10.6 mm³).

CONCLUSIONS

RTGE is a practicable, substance-sparing method performed in comparable time as CONV. Moreover, RTGE seems to be independent of operator experience.

Accuracy and Efficiency of 3-dimensional Dynamic Navigation System for Removal of Fiber Post from Root Canal-Treated Teeth

INTRODUCTION

The purpose of this study was to investigate the accuracy and efficiency of the 3-dimensional dynamic navigation system (DNS) compared with the freehand technique (FH) when removing fiber posts from root canal-treated teeth.

METHODS

Twenty-six maxillary teeth were included. Teeth were root canal treated and restored with Parapost Taper Lux (Coltene/Whaledent, Altstätten, Switzerland) luted with RelyX Unicem (3M ESPE, St Paul, MN). A core buildup was then performed using Paracore (Coltene/Whaledent). Teeth were mounted in tissue-denuded cadaver maxillae. Teeth were divided into 2 groups: the DNS group (n = 13) and the FH group (n = 13). Cone-beam computed tomographic scans were taken pre- and postoperatively. The drilling path and depth were planned virtually using X-guide software (X-Nav Technologies, Lansdale, PA) in both groups. For the DNS group, drilling was guided with X-Nav software and the FH group under a dental operating microscope. Global coronal and apical deviations, angular deflection, operation time, and the number of mishaps were compared between the groups to determine the accuracy and efficiency. The 3-dimensional volume (mm³) of all teeth was calculated before and after post removal using the Mimics Innovation Suite (Materialise NV, Leuven, Belgium). The Shapiro-Wilk, 1-way analysis of variance, and Fisher exact tests were used (P < .05).

RESULTS

The DNS group showed significantly less global coronal and apical deviations and angular deflection than the FH group (P < .05). DNS required less operation time than FH. Moreover, the DNS technique had significantly less volumetric loss of tooth structure than the FH technique (P < .05).

CONCLUSIONS

The DNS was more accurate and efficient in removing fiber posts from root canal-treated teeth than the FH technique.

Accuracy and efficiency of guided root-end resection using a dynamic navigation system: a human cadaver study

AIM

To determine and compare the accuracy and efficiency of a dynamic navigation system (DNS) with a freehand (FH) technique when conducting root-end resection in a human cadaver model.

METHODOLOGY

Forty roots in cadaver heads were included and divided into two groups: DNS (n = 20) and FH (n = 20). Cone beam computed tomography (CBCT) scans of all teeth were taken. The drilling path and depth were planned virtually to using the X-guide software (X-Nav Technologies, Lansdale, PA, USA). Osteotomy and root-end resection were done under navigation in the DNS group, and freehand under the dental operating microscope in the FH group. Post-operative CBCTs were taken. Linear deviations, angular deflection, time of operation and number of mishaps were compared with determine the accuracy and efficiency. Shapiro-Wilk, one-way ANOVA and Fisher exact tests were used (P < 0.05).

RESULTS

Linear deviations, angular deflection and operation time were significantly less in the DNS group (P < 0.05). The number of mishaps was not different between the two groups (P > 0.05). Subgroup analyses revealed that the distance of >5 mm from buccal cortical plate was significantly associated with lower accuracy, increased operation time and greater incidence of mishaps in the FH group (P < 0.05), but not in the DNS group.

CONCLUSIONS

The dynamic navigation system was more accurate and more efficient in root-end resection in a cadaver model than the freehand technique. The distance of the roots from the buccal cortical plate had a significant negative impact on the accuracy and efficacy of the root-end resection procedure when using the freehand technique. The dynamic navigation system has the potential to be a safe and reliable technological addition to endodontic microsurgery.